Radial location of bearings

If the load carrying capacity of a bearing is to be fully exploited, its rings or washers should be fully supported around their complete circumference and across the entire width of the raceway. The support, which should be firm and even, can be provided by a cylindrical or tapered seat, as appropriate or, for thrust bearing washers, by a flat (plane) support surface. This means that bearing seats should be manufactured to adequate tolerance classes and uninterrupted by grooves, holes or other features, unless the seat is prepared for the oil injection method. In addition, the bearing rings should be reliably secured to prevent them from turning on or in their seats under load.

In general, satisfactory radial location and adequate support can only be obtained when the rings are mounted with an appropriate degree of interference (→ Bearing clearance and Bearing preload). Inadequately or incorrectly secured bearing rings generally cause damage to the bearing and mating components. However, when axial displacement (as with a non-locating bearing) or easy mounting and dismounting are required, an interference fit cannot always be used. In cases where a loose fit is necessary, but an interference fit would normally be required, special precautions are necessary to limit the fretting wear that inevitably results from creep (the bearing ring turning on its seat). This can be done, for example, by surface hardening the bearing seat and abutments, lubricating mating surfaces via special lubrication grooves, or providing locating slots in the bearing ring side faces to accommodate keys or other holding devices (fig. 1).